This invention relates generally to global positioning system (GPS) antennas.
The widespread availability of low cost GPS receivers has spawned a myriad of GPS applications. GPS receivers are used for example by boaters to determine their position. Hikers can carry hand-held GPS receivers to locate themselves. In addition, GPS receivers for vehicle navigation are also available in personal and commercial vehicles. The GPS receiver may work with mapping software to indicate the user's position on a computer displayed map.
In order for the GPS receiver to work adequately, its active element antenna must be oriented in alignment with the earth's surface. That is, the active element should be parallel to the earth's surface when the GPS receiver is operational. With a hand-held unit, the user can simply orient the antenna in parallel alignment with the earth's surface.
However, in many other applications, it is not always practical to realign the antenna with respect to the earth's surface. For example, in GPS antennas which are mounted into vehicles, it is not possible to continually reposition the antenna. Thus, in many vehicular mounted systems, as the vehicle goes up and down hills for example, the alignment between the antenna and the earth is lost, degrading the performance of the GPS receiver.
Thus, there is a continuing need for a GPS antenna which maintains its alignment with the earth's surface.